A known drilling bit for holes in rocks comprises a shank made as a single workpiece with extension serving as a bit head with inserts of sintered carbide mounted therein by means of soldering. The parts of the inserts protruding above the head constitute the drill points of the bit, arranged symmetrically on the front face thereof and together with a part of the head are shaped in the form of a wedge having equal angles in relation to a plane passing through the drill point edge of the bit and parallel to the main axis of the bit. The side surfaces of the bit are parallel to each other and perpendicular to the cross-section of the bit, whereby the basic surface of the insert is perpendicular to the side surfaces of the bit. Between the drill points, in the main axis of the bit, a central flushing channel is provided, and between the drill points, in the side surface of the bit, pockets are made, to remove the drillings material. Said pockets are connected above the flushing channels with the cylindrical space of the shank. Moreover, the cross-section of the part of the insert, situated below the drill point, lying in the plane of symmetry of said part of the insert, perpendicular to the cross-sectional plane thereof, has the form of an irregular quadrangle.
A disadvantage of said bit consists in the frequent spalling of the drill points and breaking of the sintered carbide inserts in the course of drilling holes in rock, caused by occurrence of high stress concentrations in the corners of the plate bases. Furthermore, the rock core formed in the central part of the hole being drilled causes a shearing of the solder and pushing the plates outside the bit head.